A hand-held centrifuge apparatus for sedimenting a fluid suspension in a sample tube, the sample tube being subjected to centrifugation at an acute angle to the axis of rotation. An electronic circuit activates an electric motor for a preselected time period as a function of voltage supplied by a battery to the motor to provide a predetermined degree of centrifugation to the sample. A voltage tester periodically tests the voltage in the circuit to assure that adequate voltage is being supplied by the battery. A deactivation circuit is actuated if inadequate voltage is sensed and a disabling circuit disables the electronic circuit until adequate voltage is again available. The disabling circuit is masked during acceleration to preclude deactivating the circuit when the motor is in acceleration.